Chemical Composition, Antimicrobial, and Cytotoxic Activities of the Essential Oil of Otostegia fruticosa subsp schimperi from Yemen

The leaf essential oil of Otostegia fruticosa subsp. schimperi (Lamiaceae) was obtained by hydrodistillation and analyzed by gas chromatography - mass spectrometry (GC-MS). The major components in the leaf oil were r-cadinol (9.3%), beta-caryophyllene (8.8%), and bornyl formate (5.2%) as well as two unidentified diterpenoids (12.7% and 9.4%, respectively). The leaf oil was screened for antibacterial (Bacillus cereus, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa), antifungal (Aspergillus niger, Candida albicans, and Botrytis cinerea), and cytotoxic (MCF-7 and MDA-MB-231) activity. The oil did not show antimicrobial or antifungal activity, but it showed very good cytotoxicity against MCF-7 (IC50 = 55.1 mu g/mL) and MDA-MB-231 (IC50 = 70.3 mu g/mL) cell lines.